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Restier-Verlet J, Joubert A, Ferlazzo ML, Granzotto A, Sonzogni L, Al-Choboq J, El Nachef L, Le Reun E, Bourguignon M, Foray N. X-rays-Induced Bystander Effect Consists in the Formation of DNA Breaks in a Calcium-Dependent Manner: Influence of the Experimental Procedure and the Individual Factor. Biomolecules 2023; 13:biom13030542. [PMID: 36979480 PMCID: PMC10046354 DOI: 10.3390/biom13030542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 02/22/2023] [Accepted: 03/07/2023] [Indexed: 03/19/2023] Open
Abstract
Radiation-induced bystander effects (RIBE) describe the biological events occurring in non-targeted cells in the vicinity of irradiated ones. Various experimental procedures have been used to investigate RIBE. Interestingly, most micro-irradiation experiments have been performed with alpha particles, whereas most medium transfers have been done with X-rays. With their high fluence, synchrotron X-rays represent a real opportunity to study RIBE by applying these two approaches with the same radiation type. The RIBE induced in human fibroblasts by the medium transfer approach resulted in a generation of DNA double-strand breaks (DSB) occurring from 10 min to 4 h post-irradiation. Such RIBE was found to be dependent on dose and on the number of donor cells. The RIBE induced with the micro-irradiation approach produced DSB with the same temporal occurrence. Culture media containing high concentrations of phosphates were found to inhibit RIBE, while media rich in calcium increased it. The contribution of the RIBE to the biological dose was evaluated after synchrotron X-rays, media transfer, micro-irradiation, and 6 MeV photon irradiation mimicking a standard radiotherapy session: the RIBE may represent less than 1%, about 5%, and about 20% of the initial dose, respectively. However, RIBE may result in beneficial or otherwise deleterious effects in surrounding tissues according to their radiosensitivity status and their capacity to release Ca2+ ions in response to radiation.
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Affiliation(s)
- Juliette Restier-Verlet
- INSERM U1296 unit “Radiation: Defense/Health/Environment” Centre Léon-Bérard, 69008 Lyon, France
| | - Aurélie Joubert
- INSERM U1296 unit “Radiation: Defense/Health/Environment” Centre Léon-Bérard, 69008 Lyon, France
| | - Mélanie L. Ferlazzo
- INSERM U1296 unit “Radiation: Defense/Health/Environment” Centre Léon-Bérard, 69008 Lyon, France
| | - Adeline Granzotto
- INSERM U1296 unit “Radiation: Defense/Health/Environment” Centre Léon-Bérard, 69008 Lyon, France
| | - Laurène Sonzogni
- INSERM U1296 unit “Radiation: Defense/Health/Environment” Centre Léon-Bérard, 69008 Lyon, France
| | - Joëlle Al-Choboq
- INSERM U1296 unit “Radiation: Defense/Health/Environment” Centre Léon-Bérard, 69008 Lyon, France
| | - Laura El Nachef
- INSERM U1296 unit “Radiation: Defense/Health/Environment” Centre Léon-Bérard, 69008 Lyon, France
| | - Eymeric Le Reun
- INSERM U1296 unit “Radiation: Defense/Health/Environment” Centre Léon-Bérard, 69008 Lyon, France
| | - Michel Bourguignon
- INSERM U1296 unit “Radiation: Defense/Health/Environment” Centre Léon-Bérard, 69008 Lyon, France
- Department of Biophysics and Nuclear Medicine, Université Paris Saclay Versailles St Quentin en Yvelines, 78035 Versailles, France
| | - Nicolas Foray
- INSERM U1296 unit “Radiation: Defense/Health/Environment” Centre Léon-Bérard, 69008 Lyon, France
- Correspondence: ; Tel.: +33-4-78-78-28-28
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Pakniyat F, Mozdarani H, Nedaie HA, Mahmoudzadeh A, Salimi M, Gholami S. Bystander Response Following High-Dose X-irradiation; Time-dependent Nature of GammaH2AX Foci and Cell Death Consequences. J Biomed Phys Eng 2023; 13:17-28. [PMID: 36818004 PMCID: PMC9923241 DOI: 10.31661/jbpe.v0i0.2001-1053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Accepted: 05/07/2020] [Indexed: 01/31/2023]
Abstract
Background The paradigm shifts in target theory could be defined as the radiation-triggered bystander response in which the radiation deleterious effects occurred in the adjacent cells. Objective This study aims to assess bystander response in terms of DNA damage and their possible cell death consequences following high-dose radiotherapy. Temporal characteristics of gH2AX foci as a manifestation of DNA damage were also evaluated. Material and Methods In this experimental study, bystander response was investigated in human carcinoma cells of HeLa and HN5, neighboring those that received high doses. Medium transfer was performed from 10 Gy-irradiated donors to 1.5 Gy-irradiated recipients. GammaH2AX foci, clonogenic and apoptosis assays were investigated. The gH2AX foci time-point study was implemented 1, 4, and 24 h after the medium exchange. Results DNA damage was enhanced in HeLa and HN5 bystander cells with the ratio of 1.27 and 1.72, respectively, which terminated in more than two-fold clonogenic survival decrease, along with gradual apoptosis increase. GammH2AX foci temporal characterization revealed maximum foci scoring at the 1 h time-point in HeLa, and also 4 h in HN5, which remained even 24 h after the medium sharing in higher level than the control group. Conclusion The time-dependent nature of bystander-induced gH2AX foci as a DNA damage surrogate marker was highlighted with the persistent foci at 24 h. considering an outcome of bystander-induced DNA damage, predominant role of clonogenic cell death was also elicited compared to apoptosis. Moreover, the role of high-dose bystander response observed in the current work clarified bystander potential implications in radiotherapy.
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Affiliation(s)
- Fatemeh Pakniyat
- Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran
| | - Hossein Mozdarani
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Hassan Ali Nedaie
- Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran
- Radiation Oncology Research Center, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Aziz Mahmoudzadeh
- Department of Bioscience and Biotechnology, Malek-Ashtar University of Technology, Tehran, Iran
| | - Mahdieh Salimi
- Department of Medical Genetics, Medical Biotechnology Institute, National Institute of Genetic Engineering and Biotechnology, Tehran, Iran
| | - Somayeh Gholami
- Radiation Oncology Research Center, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran
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Wang R, Zhou T, Liu W, Zuo L. Molecular mechanism of bystander effects and related abscopal/cohort effects in cancer therapy. Oncotarget 2018; 9:18637-18647. [PMID: 29719632 PMCID: PMC5915099 DOI: 10.18632/oncotarget.24746] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Accepted: 02/25/2018] [Indexed: 12/17/2022] Open
Abstract
Cancer cells subjected to ionizing radiation may release signals which can influence nearby non-irradiated cells, termed bystander effects. The transmission of bystander effects among cancer cells involves the activation of inflammatory cytokines, death ligands, and reactive oxygen/nitrogen species. In addition to bystander effects, two other forms of non-target effects (NTEs) have been identified in radiotherapy, as one is called cohort effects and the other is called abscopal effects. Cohort effects represent the phenomenon where irradiated cells can produce signals that reduce the survival of neighboring cells within an irradiated volume. The effects suggest the importance of cellular communication under irradiation with non-uniform dose distribution. In contrast, abscopal effects describe the NTEs that typically occur in non-irradiated cells distant from an irradiated target. These effects can be mediated primarily by immune cells such as T cells. Clinical trials have shown that application of radiation along with immunotherapy may enhance abscopal effects and improve therapeutic efficacy on non-target lesions outside an irradiated field. According to NTEs, cell viability is reduced not only by direct irradiation effects, but also due to signals emitted from nearby irradiated cells. A clinical consideration of NTEs could have a revolutionary impact on current radiotherapy via the establishment of more efficient and less toxic radiobiological models for treatment planning compared to conventional models. Thus, we will review the most updated findings about these effects and outline their mechanisms and potential applications in cancer treatment with a special focus on the brain, lung, and breast cancers.
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Affiliation(s)
- Rong Wang
- Department of Radiation, Fifth People's Hospital of Qinghai Province, Xi Ning, Qing Hai 810007, China.,Radiologic Sciences and Respiratory Therapy Division, School of Health and Rehabilitation Sciences, The Ohio State University College of Medicine, Columbus, Ohio 43210, USA
| | - Tingyang Zhou
- Radiologic Sciences and Respiratory Therapy Division, School of Health and Rehabilitation Sciences, The Ohio State University College of Medicine, Columbus, Ohio 43210, USA.,Interdisciplinary Biophysics Graduate Program, The Ohio State University, Columbus, Ohio 43210, USA
| | - Wei Liu
- Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, Arizona 85054, USA
| | - Li Zuo
- Radiologic Sciences and Respiratory Therapy Division, School of Health and Rehabilitation Sciences, The Ohio State University College of Medicine, Columbus, Ohio 43210, USA.,Interdisciplinary Biophysics Graduate Program, The Ohio State University, Columbus, Ohio 43210, USA
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Štefančíková L, Lacombe S, Salado D, Porcel E, Pagáčová E, Tillement O, Lux F, Depeš D, Kozubek S, Falk M. Effect of gadolinium-based nanoparticles on nuclear DNA damage and repair in glioblastoma tumor cells. J Nanobiotechnology 2016; 14:63. [PMID: 27464501 PMCID: PMC4964094 DOI: 10.1186/s12951-016-0215-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 07/18/2016] [Indexed: 12/03/2022] Open
Abstract
Background Tumor targeting of radiotherapy represents a great challenge. The addition of multimodal nanoparticles, such as 3 nm gadolinium-based nanoparticles (GdBNs), has been proposed as a promising strategy to amplify the effects of radiation in tumors and improve diagnostics using the same agents. This singular property named theranostic is a unique advantage of GdBNs. It has been established that the amplification of radiation effects by GdBNs appears due to fast electronic processes. However, the influence of these nanoparticles on cells is not yet understood. In particular, it remains dubious how nanoparticles activated by ionizing radiation interact with cells and their constituents. A crucial question remains open of whether damage to the nucleus is necessary for the radiosensitization exerted by GdBNs (and other nanoparticles). Methods We studied the effect of GdBNs on the induction and repair of DNA double-strand breaks (DSBs) in the nuclear DNA of U87 tumor cells irradiated with γ-rays. For this purpose, we used currently the most sensitive method of DSBs detection based on high-resolution confocal fluorescence microscopy coupled with immunodetection of two independent DSBs markers. Results We show that, in the conditions where GdBNs amplify radiation effects, they remain localized in the cytoplasm, i.e. do not penetrate into the nucleus. In addition, the presence of GdBNs in the cytoplasm neither increases induction of DSBs by γ-rays in the nuclear DNA nor affects their consequent repair. Conclusions Our results suggest that the radiosensitization mediated by GdBNs is a cytoplasmic event that is independent of the nuclear DNA breakage, a phenomenon commonly accepted as the explanation of biological radiation effects. Considering our earlier recognized colocalization of GdBNs with the lysosomes and endosomes, we revolutionary hypothesize here about these organelles as potential targets for (some) nanoparticles. If confirmed, this finding of cytoplasmically determined radiosensitization opens new perspectives of using nano-radioenhancers to improve radiotherapy without escalating the risk of pathologies related to genetic damage.
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Affiliation(s)
- Lenka Štefančíková
- Department of Cell Biology and Radiobiology, Institute of Biophysics of ASCR, Brno, Czech Republic. .,Institute des Sciences Moléculaires d'Orsay (ISMO), Université Paris Sud 11, CNRS, Université Paris Saclay, Bât 351, 91405, Orsay Cedex, France.
| | - Sandrine Lacombe
- Institute des Sciences Moléculaires d'Orsay (ISMO), Université Paris Sud 11, CNRS, Université Paris Saclay, Bât 351, 91405, Orsay Cedex, France
| | - Daniela Salado
- Institute des Sciences Moléculaires d'Orsay (ISMO), Université Paris Sud 11, CNRS, Université Paris Saclay, Bât 351, 91405, Orsay Cedex, France
| | - Erika Porcel
- Institute des Sciences Moléculaires d'Orsay (ISMO), Université Paris Sud 11, CNRS, Université Paris Saclay, Bât 351, 91405, Orsay Cedex, France
| | - Eva Pagáčová
- Department of Cell Biology and Radiobiology, Institute of Biophysics of ASCR, Brno, Czech Republic
| | - Olivier Tillement
- Institut Lumière Matière, Université Claude Bernard Lyon 1, CNRS, 69622, Villeurbanne Cedex, France
| | - François Lux
- Institut Lumière Matière, Université Claude Bernard Lyon 1, CNRS, 69622, Villeurbanne Cedex, France
| | - Daniel Depeš
- Department of Cell Biology and Radiobiology, Institute of Biophysics of ASCR, Brno, Czech Republic
| | - Stanislav Kozubek
- Department of Cell Biology and Radiobiology, Institute of Biophysics of ASCR, Brno, Czech Republic
| | - Martin Falk
- Department of Cell Biology and Radiobiology, Institute of Biophysics of ASCR, Brno, Czech Republic.
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Mothersill C, Seymour C. Radiation-induced non-targeted effects: some open questions. RADIATION PROTECTION DOSIMETRY 2015; 166:125-130. [PMID: 25935010 DOI: 10.1093/rpd/ncv155] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The existence of non-targeted effects (NTEs) of radiation (genomic instability and bystander effects) has been generally accepted for >20 y; however, there is research, which was largely ignored going back to 1915 reporting these effects. Despite today's general acceptance of the phenomenon of NTE, there is little agreement about the mechanisms involved and the implications in radiation biology and radiation protection. The aim of this review was to consider some of the odd data, which have been published in the field with a view to obtaining insights or stimulating new ways of thinking about this field. By highlighting some key challenges and controversies, concerning the mechanisms and more importantly, the reason these effects exist, current ideas about the wider implications of NTEs in evolution and biology are also discussed.
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Affiliation(s)
- Carmel Mothersill
- Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, ON, Canada
| | - Colin Seymour
- Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, ON, Canada
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6
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Smith RW, Seymour CB, Moccia RD, Mothersill CE. Tissue-specific effects of acute aluminium exposure on the radiation-induced bystander effect in rainbow trout (Oncorhynchus mykiss, Walbaum). Int J Radiat Biol 2015; 91:715-23. [DOI: 10.3109/09553002.2015.1062573] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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7
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Martin OA, Redon CE, Dickey JS, Nakamura AJ, Bonner WM. Para-inflammation mediates systemic DNA damage in response to tumor growth. Commun Integr Biol 2014. [DOI: 10.4161/cib.13942] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
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8
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Marín A, Martín M, Liñán O, Alvarenga F, López M, Fernández L, Büchser D, Cerezo L. Bystander effects and radiotherapy. Rep Pract Oncol Radiother 2014; 20:12-21. [PMID: 25535579 DOI: 10.1016/j.rpor.2014.08.004] [Citation(s) in RCA: 111] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 06/16/2014] [Accepted: 08/06/2014] [Indexed: 12/18/2022] Open
Abstract
Radiation-induced bystander effects are defined as biological effects expressed after irradiation by cells whose nuclei have not been directly irradiated. These effects include DNA damage, chromosomal instability, mutation, and apoptosis. There is considerable evidence that ionizing radiation affects cells located near the site of irradiation, which respond individually and collectively as part of a large interconnected web. These bystander signals can alter the dynamic equilibrium between proliferation, apoptosis, quiescence or differentiation. The aim of this review is to examine the most important biological effects of this phenomenon with regard to areas of major interest in radiotherapy. Such aspects include radiation-induced bystander effects during the cell cycle under hypoxic conditions when administering fractionated modalities or combined radio-chemotherapy. Other relevant aspects include individual variation and genetics in toxicity of bystander factors and normal tissue collateral damage. In advanced radiotherapy techniques, such as intensity-modulated radiation therapy (IMRT), the high degree of dose conformity to the target volume reduces the dose and, therefore, the risk of complications, to normal tissues. However, significant doses can accumulate out-of-field due to photon scattering and this may impact cellular response in these regions. Protons may offer a solution to reduce out-of-field doses. The bystander effect has numerous associated phenomena, including adaptive response, genomic instability, and abscopal effects. Also, the bystander effect can influence radiation protection and oxidative stress. It is essential that we understand the mechanisms underlying the bystander effect in order to more accurately assess radiation risk and to evaluate protocols for cancer radiotherapy.
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Affiliation(s)
- Alicia Marín
- Department of Radiation Oncology, Hospital Universitario de la Princesa, Madrid, Spain
| | - Margarita Martín
- Department of Radiation Oncology, Hospital Universitario de la Princesa, Madrid, Spain
| | - Olga Liñán
- Department of Radiation Oncology, Hospital Universitario de la Princesa, Madrid, Spain
| | - Felipe Alvarenga
- Department of Radiation Oncology, Hospital Universitario de la Princesa, Madrid, Spain
| | - Mario López
- Department of Radiation Oncology, Hospital Universitario de la Princesa, Madrid, Spain
| | - Laura Fernández
- Department of Radiation Oncology, Hospital Universitario de la Princesa, Madrid, Spain
| | - David Büchser
- Department of Radiation Oncology, Hospital Universitario de la Princesa, Madrid, Spain
| | - Laura Cerezo
- Department of Radiation Oncology, Hospital Universitario de la Princesa, Madrid, Spain
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9
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Porcel E, Tillement O, Lux F, Mowat P, Usami N, Kobayashi K, Furusawa Y, Le Sech C, Li S, Lacombe S. Gadolinium-based nanoparticles to improve the hadrontherapy performances. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2014; 10:1601-8. [PMID: 24846523 DOI: 10.1016/j.nano.2014.05.005] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 04/25/2014] [Accepted: 05/12/2014] [Indexed: 01/04/2023]
Abstract
UNLABELLED Nanomedicine is proposed as a novel strategy to improve the performance of radiotherapy. High-Z nanoparticles are known to enhance the effects of ionizing radiation. Recently, multimodal nanoparticles such as gadolinium-based nanoagents were proposed to amplify the effects of x-rays and g-rays and to improve MRI diagnosis. For tumors sited in sensitive tissues, childhood cases and radioresistant cancers, hadrontherapy is considered superior to x-rays and g-rays. Hadrontherapy, based on fast ion radiation, has the advantage of avoiding damage to the tissues behind the tumor; however, the damage caused in front of the tumor is its major limitation. Here, we demonstrate that multimodal gadolinium-based nanoparticles amplify cell death with fast ions used as radiation. Molecular scale experiments give insights into the mechanisms underlying the amplification of radiation effects. This proof-of-concept opens up novel perspectives for multimodal nanomedicine in hadrontherapy, ultimately reducing negative radiation effects in healthy tissues in front of the tumor. FROM THE CLINICAL EDITOR Gadolinium-chelating polysiloxane nanoparticles were previously reported to amplify the anti-tumor effects of x-rays and g-rays and to serve as MRI contrast agents. Fast ion radiation-based hadrontherapy avoids damage to the tissues behind the tumor, with a major limitation of tissue damage in front of the tumor. This study demonstrates a potential role for the above nanoagents in optimizing hadrontherapy with preventive effects in healthy tissue and amplified cell death in the tumor.
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Affiliation(s)
- Erika Porcel
- Institut des Sciences Moléculaires d'Orsay, Université Paris Sud, CNRS, Orsay, France
| | - Olivier Tillement
- Institut Lumière Matière, Université Claude Bernard Lyon 1, CNRS, Villeurbanne, France
| | - François Lux
- Institut Lumière Matière, Université Claude Bernard Lyon 1, CNRS, Villeurbanne, France
| | - Pierre Mowat
- Institut Lumière Matière, Université Claude Bernard Lyon 1, CNRS, Villeurbanne, France
| | - Noriko Usami
- Photon Factory, Institute of Material Science, High Energy Accelerator Research Organization, Oho 1, Tsukuba, Ibaraki, Japan
| | - Katsumi Kobayashi
- Photon Factory, Institute of Material Science, High Energy Accelerator Research Organization, Oho 1, Tsukuba, Ibaraki, Japan
| | - Yoshiya Furusawa
- Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, Japan
| | - Claude Le Sech
- Institut des Sciences Moléculaires d'Orsay, Université Paris Sud, CNRS, Orsay, France
| | - Sha Li
- Institut des Sciences Moléculaires d'Orsay, Université Paris Sud, CNRS, Orsay, France
| | - Sandrine Lacombe
- Institut des Sciences Moléculaires d'Orsay, Université Paris Sud, CNRS, Orsay, France.
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Sprung CN, Ivashkevich A, Forrester HB, Redon CE, Georgakilas A, Martin OA. Oxidative DNA damage caused by inflammation may link to stress-induced non-targeted effects. Cancer Lett 2013; 356:72-81. [PMID: 24041866 DOI: 10.1016/j.canlet.2013.09.008] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2013] [Revised: 08/30/2013] [Accepted: 09/08/2013] [Indexed: 12/25/2022]
Abstract
A spectrum of radiation-induced non-targeted effects has been reported during the last two decades since Nagasawa and Little first described a phenomenon in cultured cells that was later called the "bystander effect". These non-targeted effects include radiotherapy-related abscopal effects, where changes in organs or tissues occur distant from the irradiated region. The spectrum of non-targeted effects continue to broaden over time and now embrace many types of exogenous and endogenous stressors that induce a systemic genotoxic response including a widely studied tumor microenvironment. Here we discuss processes and factors leading to DNA damage induction in non-targeted cells and tissues and highlight similarities in the regulation of systemic effects caused by different stressors.
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Affiliation(s)
- Carl N Sprung
- Centre for Innate Immunity and Infectious Diseases, Monash Institute of Medical Research, Monash University, Clayton, Victoria, Australia.
| | - Alesia Ivashkevich
- Centre for Innate Immunity and Infectious Diseases, Monash Institute of Medical Research, Monash University, Clayton, Victoria, Australia
| | - Helen B Forrester
- Centre for Innate Immunity and Infectious Diseases, Monash Institute of Medical Research, Monash University, Clayton, Victoria, Australia
| | - Christophe E Redon
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
| | - Alexandros Georgakilas
- Department of Physics, School of Applied Mathematical and Physical Sciences, National Technical University of Athens, Zografou Campus, Athens, Greece
| | - Olga A Martin
- Department of Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia; Molecular Radiation Biology Laboratory, Peter MacCallum Cancer Centre and the University of Melbourne, Victoria, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Victoria, Australia
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11
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Ivashkevich A, Redon CE, Nakamura AJ, Martin RF, Martin OA. Use of the γ-H2AX assay to monitor DNA damage and repair in translational cancer research. Cancer Lett 2012; 327:123-33. [PMID: 22198208 PMCID: PMC3329565 DOI: 10.1016/j.canlet.2011.12.025] [Citation(s) in RCA: 335] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 12/11/2011] [Accepted: 12/14/2011] [Indexed: 12/30/2022]
Abstract
Formation of γ-H2AX in response to DNA double stranded breaks (DSBs) provides the basis for a sensitive assay of DNA damage in human biopsies. The review focuses on the application of γ-H2AX-based methods to translational studies to monitor the clinical response to DNA targeted therapies such as some forms of chemotherapy, external beam radiotherapy, radionuclide therapy or combinations thereof. The escalating attention on radiation biodosimetry has also highlighted the potential of the assay including renewed efforts to assess the radiosensitivity of prospective radiotherapy patients. Finally the γ-H2AX response has been suggested as a basis for an in vivo imaging modality.
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Affiliation(s)
- Alesia Ivashkevich
- Laboratory of Molecular Radiation Biology, Peter MacCallum Cancer Centre, Melbourne, Australia
| | - Christophe E. Redon
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, USA
| | - Asako J. Nakamura
- Department of Anatomy and Cell Biology, Osaka Medical College, Osaka, Japan
| | - Roger F. Martin
- Laboratory of Molecular Radiation Biology, Peter MacCallum Cancer Centre, Melbourne, Australia
| | - Olga A. Martin
- Laboratory of Molecular Radiation Biology, Peter MacCallum Cancer Centre, Melbourne, Australia
- Department of Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, Australia
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Mothersill C, Bristow RG, Harding SM, Smith RW, Mersov A, Seymour CB. A role for p53 in the response of bystander cells to receipt of medium borne signals from irradiated cells. Int J Radiat Biol 2011; 87:1120-5. [DOI: 10.3109/09553002.2011.610866] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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13
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Induction of the bystander effect in Chinese hamster V79 cells by actinomycin D. Toxicol Lett 2011; 202:178-85. [DOI: 10.1016/j.toxlet.2011.02.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Revised: 01/31/2011] [Accepted: 02/01/2011] [Indexed: 11/23/2022]
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14
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Martin OA, Redon CE, Dickey JS, Nakamura AJ, Bonner WM. Para-inflammation mediates systemic DNA damage in response to tumor growth. Commun Integr Biol 2011; 4:78-81. [PMID: 21509186 PMCID: PMC3073278 DOI: 10.4161/cib.4.1.13942] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Accepted: 10/14/2010] [Indexed: 12/24/2022] Open
Abstract
The radiation induced bystander effect is a well-accepted consequence of ionizing radiation exposure. However, it has become clear that bystander responses in vitro can result from a number of stress stimuli. We had reported that media conditioned on tumor cell cultures induced a bystander effect in recipient normal cell cultures and asked whether an analogous process could occur in vivo-could the presence of a tumor induce DNA damage in distant tissues. We recently demonstrated the presence of a distant bystander DNA damage response in vivo in the gastrointestinal organs and skin of mice implanted with subcutaneous tumors. The activation of inflammatory macrophages through the cytokine CCL2 was found to be required for this distant genotoxic response. These results shed new light on the consequences of tumor growth to distant parts of the body and highlight the potential for possible medical interventions to mitigate the effect of cancers.
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Affiliation(s)
- Olga A Martin
- Laboratory of Molecular Pharmacology; Center for Cancer Research; National Cancer Institute; Bethesda, MD USA
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Dauer LT, Brooks AL, Hoel DG, Morgan WF, Stram D, Tran P. Review and evaluation of updated research on the health effects associated with low-dose ionising radiation. RADIATION PROTECTION DOSIMETRY 2010; 140:103-136. [PMID: 20413418 DOI: 10.1093/rpd/ncq141] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
While radiation health risks at low doses have traditionally been estimated from high-dose studies, we have reviewed recent literature and concluded that the mechanisms of action for many biological endpoints may be different at low doses from those observed at high doses; that acute doses <100 mSv may be too small to allow epidemiological detection of excess cancers given the background of naturally occurring cancers; that low-dose radiation research should use holistic approaches such as systems-based methods to develop models that define the shape of the dose-response relationship; and that these results should be combined with the latest epidemiology to produce a comprehensive understanding of radiation effects that addresses both damage, likely with a linear effect, and response, possibly with non-linear consequences. Continued research is needed to understand how radiobiology and epidemiology advances should be used to effectively model radiation worker risks.
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Affiliation(s)
- Lawrence T Dauer
- Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.
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Abstract
This review considers the implications for environmental health and ecosystem sustainability, of new developments in radiobiology and ecotoxicology. Specifically it considers how the non-targeted effects of low doses of radiation, which are currently being scrutinized experimentally, not only mirror similar effects from low doses of chemical stressors but may actually lead to unpredictable emergent effects at higher hierarchical levels. The position is argued that non-targeted effects are mechanistically important in coordinating phased hierarchical transitions (i.e. transitions which occur in a regulated sequence). The field of multiple stressors (both radiation and chemical) is highly complex and agents can interact in an additive, antagonist or synergistic manner. The outcome following low dose multiple stressor exposure also is impacted by the context in which the stressors are received, perceived or communicated by the organism or tissue. Modern biology has given us very sensitive methods to examine changes following stressor interaction with biological systems at several levels of organization but the translation of these observations to ultimate risk remains difficult to resolve. Since multiple stressor exposure is the norm in the environment, it is essential to move away from single stressor-based protection and to develop tools, including legal instruments, which will enable us to use response-based risk assessment. Radiation protection in the context of multiple stressors includes consideration of humans and non-humans as separate groups requiring separate assessment frameworks. This is because for humans, individual survival and prevention of cancer are paramount but for animals, it is considered sufficient to protect populations and cancer is not of concern. The need to revisit this position is discussed not only from the environmental perspective but also from the human health perspective because the importance of "pollution" (a generic term for multiple environmental stressors) as a cause of non-cancer disease is increasingly being recognized. Finally a way forward involving experimental assessment of biomarker performance to lead to a theoretical framework allowing modeling is suggested.
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Affiliation(s)
- Carmel Mothersill
- Medical Physics and Applied Radiation Sciences Department, McMaster University, Hamilton, Ontario L8S 4K1, Canada.
| | - Colin Seymour
- Medical Physics and Applied Radiation Sciences Department, McMaster University, Hamilton, Ontario L8S 4K1, Canada
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Dickey JS, Baird BJ, Redon CE, Sokolov MV, Sedelnikova OA, Bonner WM. Intercellular communication of cellular stress monitored by gamma-H2AX induction. Carcinogenesis 2009; 30:1686-95. [PMID: 19651821 DOI: 10.1093/carcin/bgp192] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
When cells are exposed to ionizing radiation (IR), unexposed cells that share media with damaged cells exhibit similar effects to irradiated cells including increased levels of DNA double-strand breaks (DSBs). Hypothesizing that this effect, known as the radiation-induced bystander effect, may be a specific instance of communication between damaged and undamaged cells regardless of damage source, we demonstrated that exposure of target cells to non-IR induces bystander damage in non-targeted cells as measured by gamma-H2AX and 53BP1 focal formation. Initially, bystander damage was found primarily in S-phase cells, but at later times, non-S-phase cells were also affected. In addition, media from undamaged malignant and senescent cells also was found to induce DSBs in primary cultures. Media conditioned on cells targeted with either ionizing or non-IR as well as on undamaged malignant and senescent cells contained elevated levels of several cytokines. One of these, transforming growth factor beta (TGF-beta), and nitric oxide (NO) were found to elevate numbers of gamma-H2AX/53BP1 foci in normal cell cultures similar to levels found in bystander cells, and this elevation was abrogated by NO synthase inhibitors, TGF-beta blocking antibody and antioxidants. These findings support the hypothesis that damage in bystander cells results from their exposure to cytokines or reactive compounds released from stressed cells, regardless of damage source. These results have implications for oncogenesis in that they indicate that damaged normal cells or undamaged tumor cells may induce genomic instability, leading to an increased risk of oncogenic transformation in other cells with which they share media or contact directly.
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Affiliation(s)
- Jennifer S Dickey
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20952, USA.
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Fournier C, Barberet P, Pouthier T, Ritter S, Fischer B, Voss KO, Funayama T, Hamada N, Kobayashi Y, Taucher-Scholz G. No evidence for DNA and early cytogenetic damage in bystander cells after heavy-ion microirradiation at two facilities. Radiat Res 2009; 171:530-40. [PMID: 19580488 DOI: 10.1667/rr1457.1] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The occurrence of bystander effects has challenged the evaluation of risk for heavy ions, mainly in the context of space exploration and the increasing application of carbon ions in radiotherapy. In the present study, we addressed whether heavy-ion-induced DNA and cytogenetic damage is detectable in bystander cells. The formation of gamma-H2AX foci, sister chromatid exchanges and micronuclei were used as markers of damage to DNA. Normal human fibroblasts were exposed to low fluences of carbon and uranium ions, and alternatively single cells were targeted with heavy ions using the GSI microbeam. We did not observe a significant increase in the bystander formation of gamma-H2AX foci, sister chromatid exchanges or micronuclei. In addition, we performed for the first time parallel experiments at two microbeam facilities (GSI, JAEA) using the same cell line, culture conditions and irradiation protocols. No significant enhancement of the micronucleus frequencies in bystander cells was detected after targeted carbon-ion irradiation, confirming the results. Details regarding the history, culture conditions or support of the cells might be affecting the detection of bystander effects. On the other hand, the potential X-ray- and heavy-ion-induced bystander effects investigated herein clearly do not exceed the experimental error and thus are either lacking or are less pronounced than the effects reported in the literature for similar end points after alpha-particle and X-ray exposure.
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Affiliation(s)
- C Fournier
- Department of Biophysics, Gesellschaft für Schwerionenforschung, 64291 Darmstadt, Germany.
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Zhou H, Hong M, Chai Y, Hei TK. Consequences of cytoplasmic irradiation: studies from microbeam. JOURNAL OF RADIATION RESEARCH 2009; 50 Suppl A:A59-A65. [PMID: 19346686 PMCID: PMC3664637 DOI: 10.1269/jrr.08120s] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The prevailing dogma for radiation biology is that genotoxic effects of ionizing radiation such as mutations and carcinogenesis are attributed mainly to direct damage to the nucleus. However, with the development of microbeam that can target precise positions inside the cells, accumulating evidences have shown that energy deposit by radiation in nuclear DNA is not required to trigger the damage, extra-nuclear or extra-cellular radiation could induce the similar biological effects as well. This review will summarize the biological responses after cytoplasm irradiated by microbeam, and the possible mechanisms involved in cytoplasmic irradiation.
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Affiliation(s)
- Hongning Zhou
- Center for Radiological Research, Columbia University Medical Center, 630 West 168th Street, New York, NY 10032, USA.
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Groesser T, Cooper B, Rydberg B. Lack of Bystander Effects from High-LET Radiation for Early Cytogenetic End Points. Radiat Res 2008; 170:794-802. [DOI: 10.1667/rr1458.1] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Accepted: 07/28/2008] [Indexed: 11/03/2022]
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Burdak-Rothkamm S, Rothkamm K, Prise KM. ATM acts downstream of ATR in the DNA damage response signaling of bystander cells. Cancer Res 2008; 68:7059-65. [PMID: 18757420 DOI: 10.1158/0008-5472.can-08-0545] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
This study identifies ataxia-telangiectasia mutated (ATM) as a further component of the complex signaling network of radiation-induced DNA damage in nontargeted bystander cells downstream of ataxia-telangiectasia and Rad3-related (ATR) and provides a rationale for molecular targeted modulation of these effects. In directly irradiated cells, ATR, ATM, and DNA-dependent protein kinase (DNA-PK) deficiency resulted in reduced cell survival as predicted by the known important role of these proteins in sensing DNA damage. A decrease in clonogenic survival was also observed in ATR/ATM/DNA-PK-proficient, nonirradiated bystander cells, but this effect was completely abrogated in ATR and ATM but not DNA-PK-deficient bystander cells. ATM activation in bystander cells was found to be dependent on ATR function. Furthermore, the induction and colocalization of ATR, 53BP1, ATM-S1981P, p21, and BRCA1 foci in nontargeted cells was shown, suggesting their involvement in bystander DNA damage signaling and providing additional potential targets for its modulation. 53BP1 bystander foci were induced in an ATR-dependent manner predominantly in S-phase cells, similar to gammaH2AX foci induction. In conclusion, these results provide a rationale for the differential modulation of targeted and nontargeted effects of radiation.
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Affiliation(s)
- Susanne Burdak-Rothkamm
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast, United Kingdom.
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Zhang Y, Zhou J, Held KD, Redmond RW, Prise KM, Liber HL. Deficiencies of double-strand break repair factors and effects on mutagenesis in directly gamma-irradiated and medium-mediated bystander human lymphoblastoid cells. Radiat Res 2008; 169:197-206. [PMID: 18220473 DOI: 10.1667/rr1189.1] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2007] [Accepted: 10/02/2007] [Indexed: 11/03/2022]
Abstract
Using RNA interference techniques to knock down key proteins in two major double-strand break (DSB) repair pathways (DNA-PKcs for nonhomologous end joining, NHEJ, and Rad54 for homologous recombination, HR), we investigated the influence of DSB repair factors on radiation mutagenesis at the autosomal thymidine kinase (TK) locus both in directly irradiated cells and in unirradiated bystander cells. We also examined the role of p53 (TP53) in these processes by using cells of three human lymphoblastoid cell lines from the same donor but with differing p53 status (TK6 is p53 wild-type, NH32 is p53 null, and WTK1 is p53 mutant). Our results indicated that p53 status did not affect either the production of radiation bystander mutagenic signals or the response to these signals. In directly irradiated cells, knockdown of DNA-PKcs led to an increased mutant fraction in WTK1 cells and decreased mutant fractions in TK6 and NH32 cells. In contrast, knockdown of DNA-PKcs led to increased mutagenesis in bystander cells regardless of p53 status. In directly irradiated cells, knockdown of Rad54 led to increased induced mutant fractions in WTK1 and NH32 cells, but the knockdown did not affect mutagenesis in p53 wild-type TK6 cells. In all cell lines, Rad54 knockdown had no effect on the magnitude of bystander mutagenesis. Studies with extracellular catalase confirmed the involvement of H2O2 in bystander signaling. Our results demonstrate that DSB repair factors have different roles in mediating mutagenesis in irradiated and bystander cells.
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Affiliation(s)
- Ying Zhang
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado, USA.
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23
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Ryan LA, Smith RW, Seymour CB, Mothersill CE. Dilution of irradiated cell conditioned medium and the bystander effect. Radiat Res 2008; 169:188-96. [PMID: 18220470 DOI: 10.1667/rr1141.1] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2007] [Accepted: 11/06/2007] [Indexed: 11/03/2022]
Abstract
While nontargeted and low-dose effects such as the bystander effect are now accepted, the mechanisms underlying the response have yet to be elucidated. It has been shown that the transfer of irradiated cell conditioned medium (ICCM) can kill cells that are not directly irradiated; however, to date the effect of ICCM concentration on cell killing has not been reported. The occurrence of a bystander effect was determined by measuring cell survival after exposure to various ICCM dilutions, using the colony-forming assay, in cells of six human cell lines with varied bystander responses and tumor/ p53 status. Autologous ICCM transfer for these cell lines induced a bystander effect as reported previously. ICCM from these cell lines was transferred to cells of a common reporter cell line (HPV-G) to investigate whether the lack of an induced bystander effect was due to their inability to generate or to respond to a bystander signal(s). ICCM from cells of four cell lines induced a bystander effect in HPV-G reporter cells, confirming that signal production is a critical factor. A saturation response was observed when ICCM was diluted. Survival was found to increase linearly until a plateau was reached and the bystander effect was abolished at 2x dilution. The effect of ICCM from the different cell lines reached a plateau at different dilutions, which were found to correlate with the cell line's radiosensitivity.
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Affiliation(s)
- Lorna A Ryan
- Medical Physics and Applied Radiation Sciences Department, McMaster University, Hamilton, Ontario, Canada L8S 4K1
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24
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Shao C, Prise KM, Folkard M. Signaling factors for irradiated glioma cells induced bystander responses in fibroblasts. Mutat Res 2008; 638:139-145. [PMID: 17977565 DOI: 10.1016/j.mrfmmm.2007.09.007] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Revised: 09/16/2007] [Accepted: 09/19/2007] [Indexed: 05/25/2023]
Abstract
The aim of this study was to investigate the signaling factor and its pathway involved in the targeted irradiation-induced bystander response from glioblastoma cells to primary fibroblasts. After co-culturing with a glioblastoma T98G population where a fraction of cells had been individually irradiated with a precise number of helium particles, additional micronucleus (MN) were induced in the non-irradiated human fibroblasts AG01522 cells and its yield was independent of irradiation dose. This bystander MN induction was eliminated by treating the cells with either aminoguanidine (AG), an iNOS inhibitor, or anti-transforming growth factor-beta1 (anti-TGF-beta1). In addition, TGF-beta1 could be released from irradiated T98G cells but this release was inhibited by AG. In consistent, TGF-beta1 could also be induced from T98G cells treated with diethylamine nitric oxide (DEANO), a donor of nitric oxide (NO). Moreover, the effect of TGF-beta1 on bystander AG01522 cells was investigated. It was found that reactive oxygen species (ROS) and MN were induced in AG01522 cells after TGF-beta1 treatment. Our results indicate that, downstream of NO, TGF-beta1 plays an important role in the targeted T98G cells induced bystander response to AG0 cells by further causing DNA damage in vicinal fibroblasts through a ROS related pathway. This study may have implications for properly evaluating the secondary effects of radiotherapy.
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Affiliation(s)
- Chunlin Shao
- Institute of Radiation Medicine, Fudan University, No. 2094 Xie-Tu Road, Shanghai 200032, China.
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25
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Smith RW, Wang J, Bucking CP, Mothersill CE, Seymour CB. Evidence for a protective response by the gill proteome of rainbow trout exposed to X-ray induced bystander signals. Proteomics 2008; 7:4171-80. [PMID: 17994622 DOI: 10.1002/pmic.200700573] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The bystander effect occurs when cells which are not directly exposed to radiation, but which receive signals from irradiated cells, respond as though they were irradiated. An X-ray induced bystander effect has been demonstrated in rainbow trout gills. Therefore, a proteomic comparison was made of gills from X-ray treated trout and trout exposed to X-ray induced bystander signals. 2-D gel analysis revealed X-ray exposure increased the expression of the cancer related protein annexin II. The proteomic changes associated with the bystander effect differed from those associated with direct radiation exposure. Expression of a hemopexin-like protein, Rho GDP dissociation inhibitor (RhoGDI) and pyruvate dehydrogenase (PDH) were increased. These proteins possess protective properties against reactive oxygen damage (a component of the bystander signal), regulate epithelial polarity and prevent lactate acidosis, respectively. There was also evidence for an increase in chromosome 1 SR-like CTD-associated factor (SCAF) protein turnover, which could suggest the protective response is transcriptionally regulated. The freshwater fish gill is a polarised barrier, separating against an external hypotonic environment. Since the maintenance of epithelial polarity is vital to gill function, these bystander effect proteomic changes could collectively protect the structural, functional and intracellular integrity of gill epithelia.
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Affiliation(s)
- Richard W Smith
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
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Hamada N, Hara T, Omura-Minamisawa M, Ni M, Funayama T, Sakashita T, Sora S, Nakano T, Kobayashi Y. Heavy-Ion Microbeam Irradiation Induces Bystander Killing of Human Cells. ACTA ACUST UNITED AC 2008. [DOI: 10.2187/bss.22.46] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Schwartz JL. Variability: the common factor linking low dose-induced genomic instability, adaptation and bystander effects. Mutat Res 2006; 616:196-200. [PMID: 17145066 DOI: 10.1016/j.mrfmmm.2006.11.016] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The characteristics of low dose radiation-induced genomic instability, adaptive responses, and bystander effects were compared in order to probe possible underlying mechanisms, and develop models for predicting response to in vivo low dose radiation exposures. While there are some features that are common to all three (e.g., absence of a true dose-response, the multiple endpoints affected by each), other characteristics appear to distinguish one from the other (e.g., TP53 involvement, LET response, influence of DNA repair). Each of the responses is also highly variable; not all cell and tissue models show the same response and there is much interindividual variation in response. Most of these studies have employed in vitro cell culture or tissue explant models, and understanding underlying mechanisms and the biological significance of these low dose-responses will require study of tissue-specific in vivo endpoints. The in vitro studies strongly suggest that modeling low dose radiation effects will be a complex process, and will likely require separate study of each of these low dose phenomena. Knowledge of instability responses, for example, may not aid in predicting other low dose effects in the same tissue.
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Affiliation(s)
- Jeffrey L Schwartz
- Department of Radiation Oncology, University of Washington Medical Center, 1959 NE Pacific, Box 356069, Seattle, WA 98195-6069, USA.
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Yun AJ, Doux JD. Stress dysfunctions as a unifying paradigm for illness: repairing relationships instead of individuals as a new gateway for medicine. Med Hypotheses 2006; 68:697-704. [PMID: 17027174 DOI: 10.1016/j.mehy.2006.08.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2006] [Accepted: 08/10/2006] [Indexed: 10/24/2022]
Abstract
Stress has been implicated as a risk factor for most diseases, but a mechanistic explanation behind such associations remains elusive. As emergent responses to stress, adaptations range from acute responses where extant system capabilities mitigate current stress, to longer-term responses where system plasticity buffers against future stress. The long compendium of human ailments manifests through a much shorter set of symptoms that may operate through the stress axis. We propose a unifying ontology for human illnesses that classifies stress dysfunctions according to types of Darwinian dysfunction - inadequate response with adequate adaptation, inadequate adaptation, inappropriate adaptation, and epiphenomena of adaptation. Examples include cancer as a bystander effect of increased biologic plasticity in response to stress, and infectious illness as a manifestation of mutually escalating stress in an otherwise commensal relationship between hosts and microbes. We explore the contributing role of man-made stresses that have emerged as humans increasingly remodel their environment. Examples include biologic decompensation associated with reliance on technology to buffer stress, and behavioral stress caused by the dislocation of kin networks that promotes illegitimate signaling. Dysfunctional relationships engender stress not only among humans, but also among individual organs; heart failure, renal failure, and carotid stenosis may represent examples of such conditions. If stress dysfunction is the Occam's razor of human illnesses, and derangements in biologic relationships induce stress dysfunctions, then the study of relationships - an incarnation of systems biology - may represent a new gateway for medicine.
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Affiliation(s)
- Anthony J Yun
- Palo Alto Institute, 470 University Avenue, Palo Alto, CA 94301, United States.
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